What are the top three modifications that I can do to increase the performance of a completely stock 7.3 non-turbo?...besides adding a turbo? Gearing?

I am looking to make the engine perform better overall and prolong the life of the motor (currently have 138,000 miles on it)...not just add HP.

This is my first diesel...so if anyone has anything to offer a newbie in regards to making this truck last please let me know...Thanks.

 

The first thing you should do is: some research in the proper forum.

Pre-Power Stroke Diesel (7.3L IDI & 6.9L) - Ford Truck Enthusiasts Forums

 

Unfortunately there's not much you can do to them besides a turbo. You can turn the fuel screw up a hair but without air mods it won't do much but smoke.

They made cams designed for Na idis back in the day, it might be hard to find them since turbos became so popular nearly immediately after the idi debut.

So, if you wanted to keep it Na and make more power you'd need to do conventional air mods to support more fuel. These mods would be cam, head and intake porting, and some type of exhaust to replace factory manifilds.

After these mods are done, then you could tune the fuel screw to match the new increased airflow.

The idis are actually impressive na, all things considered. 250 hp can prob be achieved easily with those mods. If I unhooked a turbo boot on my dodge I'd literally have something like 190 hp...when I blow a boot it's dangerously slow.

 

welcome to FTE.
there a quite a few different ways to improve performance on the IDI, first and foremost being adding a turbo.
another thing you can do in the mean time is to remove the restrictive muffler and either run no muffler, or a low back pressure muffler with a 3 inch exhaust.
opening up the intake to let it breathe easier is another addition that works well with a low back pressure exhaust system.
another good mod is to make sure the engine is running top notch, with fresh injectors and a good injector pump properly timed.
then you can also do some other engine work, like cam, and intake manifold, . one of the posters in the idi forum mentioned in post #2 is also a site sponsor vendor. justin at idiperformance.com has all kinds of goodies for the IDI at very reasonable prices.

 

When it comes to the IDI diesel of almost any make - I think there is a lot of hype thrown around about performance gains by adding bigger or more free-flowing exhaust systems. I don't buy it. A stock engine usually leaves the factory with ample exhaust to flow whatever that stock engine needs to exhaust, plus some. Now, if someone adds a turbo, or runs at higher then normal RPMs - or increases fuel delivery, etc. -then yes. More flow into the engine means more needs to get out.

Adding a turbo certainly gives great gains if you also turn up the fuel delivery. Then, more free-flowing exhaust might be helpful. This also creates the problem of lowering engine durability since it is put under more stress. Thus why Ford via International Harvester beefed up a few parts in the 7.3 when the factory turbos came out (from ATS I think). It is also why high-boost engines often run lower mechanical compression ratios then naturally aspirated engines.

Good tune is certainly important if a person has the equipment to check and/or adjust the automatic timing advance in the Stanadyne/Roosamaster injection pump. NOT an easy thing to do and it requires special tools. The automatic timing-advance system is often the first part of the injection pump to wear out in Stanadyne rotary-distributor pumps. A non-tech "by ear" test is when you start the engine cold and rev it up high - as the timing advance gets weaker - the engine will skip and break up when revved until it gets warm. With proper advance -it will rev up pretty smooth. Only way to measure for sure with a running engine is with a luminosty indicator/gauge or a Piezo-fired diesel timing light.

I had a 1985 F250 for many years with a 6.9 engine, C6 trans. and 4.10 axles. When the exhaust system finally fell off and there was no muffler or tailpipe at all, it ran just the same. Same fuel mileage and same power. Just noisier but not as bas a a gas engine would be with no muffler.

 

1.it's time for a tune up.
reman ip and a set of new injectors then have the timing set to 8 BTDC.
i recommend Conestoga Diesel Injection in PA.

2.ditch the oem air cleaner duct and install a cowl induction system.build your own or hypermax makes one.

3.ditch the oem exhaust and run at least 3" pipe with walker big truck muffler.


flush the cooling system and run new low silicate coolant with SCA's (fleetcharge is popular.) and keep the system maintained at all times.do some in depth reading on proper diesel coolant maintenance in the idi section.

happy oil burning!

but he also asked about engine longevity.when i was n/a i increased the exhaust and installed a free flow muffler and the increase was definitely noticeable.
however agree or not with that is fine.im not trying to sell ya on it.
the main advantage will be lower EGT's with an increased exhaust.n/a's can actually run hotter than a turbo engine so to keep EGT's lower which also increases engine longevity,building a freer flowing exhaust for a diesel is never a bad thing.

 

the exhaust is terrible from the factory, which isn't really a surprise considering everything was leaving the factory with terrible exhaust then. that's not even taking into account all the other stuff that caused poor performance in that era...


that said, we are talking about an engine that makes less than 200 hp. 5% increase from an exhaust would be 10 hp, which is not going to be noticeable in a 5500+ lb truck with a slushy 80's automatic.


are there gains? yes. revolutionizing your driving experience? of course not. overhyped by people who don't know anything about much? absolutely.

 

I doubt any company be it Ford, GM, or Dodge would go through the time and expense to reengineer a truck to accept a diesel, then go out and buy a diesel engine from International Harvester (or in GM's case, have Detroit Diesel make one for them, and in the first Dodge diesels - Mitsubishi) - all in the name of selling a good workhorse of a truck with optimum fuel mileage- and then rob potential power and MPGs by sticking a restrictive exhaust on there? Anybody who can do a little math can use the volumetric efficiency figures of a naturally aspirated diesel and then figure the flow needs of the exhaust. Or if no math, just use a computer-based calculator. I've checked quite a few. Found very few factory exhaust systems on HD (somewhat EPA exempt) trucks that caused the loss of any substantial horsepower with stock engine. Now - when someone had to put their first replacement system on and bought their mufflers at NAPA - all bets are off. I've found many aftermarket replacement mufflers and pipes to rob some power and raise exhaust port temps.

Many aftermarket sellers rely on buyers thinking factory parts rob power and only aftermarket is good. Even Banks rans sort of a scam with their exhaust system power "boosters" there really gained nothing until the fuel delivery was turned up, along with a few other mods (not talking about the turbo systems).

Hey, we are all free to come to our own conclusions. I for one can say for sure that when most of the exhaust system fell off my Ford F250 with the low-revving 6.9 diesel - it sounded like a garbage truck and had just the same power and MPGs as before.

Also - about the static timing specs mentioned here. What good are they if you don't know what the heck the timing advance is doing when the truck is actually being driven? All that initial static timing does is ensure the timing is correct when the engine is cranking or at low idle speed. Has pretty much nothing to do with the injection timing when the truck is being used. That is, unless you already know 100% for sure the advance curve is working properly. On older pumps, it often is not. If a person has a way to determine if the advance is weak - it can be compensated for by bumping up the initial timing. Not a perfect fix -but certainly is a cheap way to make a truck run better when actually doing work without having to remove the pump and rework it. Or sometimes, the low-pressure side of the injection pump can be turned up to make the advance work better. For that, you need a special Stanadyne fitting so you can screw a pressure gauge into the back of the injection pump. If low, it is turned up with a screw inside the pump inlet. My point is this. Suppose you have a truck and the advance is dead. You set the static timing perfect and when running - the engine is severely retarded. Supposed to be somewhere around a 26 degree advance as I recall. Pump runs half engine speed so 26 engine degrees equals 13 pump degrees. If you KNOW this, you can bump up the static timing so it's off at low idle, but much better when actually being used for work.

And of course you can just guess if the pump is suspect, you can remove it and spend maybe close to $900. Then hope it is better and still not know for sure. And that money gets you a so-called "rebuilt" pump with very few moving parts renewed in any way. Just resealed, calibration checked, and a few small parts replaced as needed. Often the low pressure pump vanes and some advance-piston parts. Often the main high-pressure parts of the pump have many, many miles on them and are re-used, as is. It gets expensive. The bright side is - these main parts can last 1,000,000 miles if the fuel has good lube. Not so sure now adays with the ultra-low sulfur stuff. I still add two-stroke oil to my tank as added insurance.

 

Exhaust system. My 1993 F350 dually had a Y Pipe, cut it and sent 2 pipes to the back with 2 short mufflers. Dropped heat in right side exhaust 300 degrees. Find a good diesel pump shop and pull the injectors and rebuild and reset injector pressure, it is about time to do them anyway. Next look where your engine is timed. I have had a lot of them come here, timed (in my opinion wrong). There are timing marks on the pump drive ( top of the valley nose of the pump and another mark on the gear cover housing.) I like to time the pump just to the left of the mark just a little. (Remember 1 or 2 degree on a diesel is a bunch) Add Standayne fuel conditioner to the fuel to lube the pump and injectors. This low sulfur fuel is not liked by these older engines. Like the unleaded fuel for an engine that needed the lead n the fuel. Make sure you service the air filter as it gets dirty, don't wait do it, same with fuel filters and buy a good grade of fuel. Sinclair, the green BP stations I have found have good fuel here. Now this is really going to upset the boys that want to spin their tires and blow black smoke. SMOKE IS NOT POWER, just unburnt fuel. Been around and worked on diesel since 1967. Drove lots of them. Had a Mack with 673 cubic inches putting 300 horse to the ground in overdrive. It would pull with most 855 cubic inch Cummings. You don't need a turbo or more fuel just make it burn what it has and you will find the drive train is not heavy enough to take what that engine can dish out. Remember it is a truck! Want a race car buy one. You must needed a truck so you bought one. Oh this will really upset the Dodge boys. Had a new Dodge 2013 maybe 2014 try my junk 7.3 the other day. In town his chipped up Cummins was standing tall from stop light to stoplight. We got outside of town, got mine to 5th gear and at 65 I pulled up beside him and give him the come on, well chipped up cummins could not handle it. Duramac same deal. But now mine is a truck, mechanical pump no turbo no power chips any that other stuff I read about and or have seen, oh also NO SMOKE. Just a truck to pull trailers and haul stuff. Depends what is hooked behind it how much fuel it uses. Hooked to the 40 foot 5th wheel Kountry Aire (20,000 empty, no water or clothes etc ) in flat land that is 7 miles a gallon. Empty truck by itself 15 to 19 miles per gallon.19 is done with interstate driving no stopping. I have 120 gallon fuel capacity so you do the math. Do I try to spin my tires, nope. It is a truck! Test drove a F450 2010 the first year Ford made their own diesel, sales man asked what I thought when we got back to dealership with it. I told him it was very nice car, not much of a truck! Remember if all things are set correctly in that engine it will perform well. Remember to go to Ford and get the water treatment so you will not have holes eaten in the cylinder walls. They have test strips at the parts house for this so you will know when this needs to be done, maybe Ford also, don't know. I go to International for parts for my 7.3 because it is International engine in a Ford truck.

 

That is great info! Thank you very much !

 

I assume many here already know this, but for those who do not . . there is no "rebuild" on the type of injectors used in these IH engines. They get brand new nozzle-tips if you want to renew them. Cost around $10 each last set I did (myself). You just unscrew the old tips, screw on the new to the injector body, and check "pop" pressure and for leak-down. There ARE a few shops selling injectors as "rebuilt" that have only been cleaned and pressures set. Those are NOT rebuilt and will not have the service life of a new injector. I yanked all mine out at 150,000 miles. All tested perfect but I replaced them all anyway. Good insurance.

Those marks don't mean much if the initial timing has been bumped up to compensate for a timing-advance not working correctly. A few degrees one way or the other before or after top-dead-center are trivial as compared to a pump that is lacking 15 degrees of advance when running down the road at 2200 RPM. Yes, if a person knows for sure the timing advance is actually working - then making sure the initial timing (using marks) is correct is important. But without knowing - the truck might run MUCH better with those marks way off. The advance is usually the first part of the pump to wear. It is all hydraulic and works off the little low-pressure vane pump inside the injector pump. There is a pressure tap in the rear of the pump where pressure can be checked but it requires a special Stanadyne adapter that costs around $10.

I've never trusted the ultra-low sulfur fuel. It has low lube once cooked and fuel sellers are required to dump in lube additive to compensate. Do they all do it as required? I have no way of knowing. Not many mechanical-distributor pumps out on the road anymore and they are the ones that suffer from low lube the most (like used in our Fords, in older GM 6.2s and 6.5s, early Cummins 3,9s and 5,9s, and a few VWs and Isuzus). In-line pumps don't suffer near as much, nor to newer common-rail systems. I use two-stroke oil. If bought in gallon jugs from Walmart, it's a cheaper additive then the official lubes and has been tested to give just as good protection at a 200 to 1 ratio.

I can't speak for newer trucks of any make. I have a stock 1992 Dodge with a 5.9 intercooled/turbo Cummins with 5 speed man. trans and 3.50 axles. It easily outpulls and outruns my stock 1994 Ford F250 with 7.3 IDI turbo, E40D trans and 4.10 axles. The Dodge also does the work using less fuel. But the Dodge rides like a Sherman tank and my Ford rides like a Cadillac. It kind of defies reason. With 4.10 axles on the Ford, you'd think it would at least pull as well as the old Dodge with 3.50s, but it does not. Still gets the job done. Just slower and with more fuel cost.

 

ford used a navastar diesel, not international harvester. different company.
GM used a GM diesel, and later an izuzu diesel. (duramax) not a detriot diesel different companies.

dodge only used the mitsushi for one year, it was a disastrous flop, and did not put a diesel in a pickup for over 7 years before going with the cummins 5.9

any vehicle made in the past 40 years has had a very restrictive exhaust on it thanks to the EPA. open the exhaust up so it is free flowing and you wake the engine up.

[QUOTE=jdemaris;15595601]Anybody who can do a little math can use the volumetric efficiency figures of a naturally aspirated diesel and then figure the flow needs of the exhaust. Or if no math, just use a computer-based calculator. I've checked quite a few. Found very few factory exhaust systems on HD (somewhat EPA exempt) trucks that caused the loss of any substantial horsepower with stock engine. Now - when someone had to put their first replacement system on and bought their mufflers at NAPA - all bets are off. I've found many aftermarket replacement mufflers and pipes to rob some power and raise exhaust port temps.[QUOTE]

we said high flow low-back pressure exhaust, not aftermarket replacement.






[QUOTE=jdemaris;15595601]Also - about the static timing specs mentioned here. What good are they if you don't know what the heck the timing advance is doing when the truck is actually being driven? All that initial static timing does is ensure the timing is correct when the engine is cranking or at low idle speed. Has pretty much nothing to do with the injection timing when the truck is being used. That is, unless you already know 100% for sure the advance curve is working properly. On older pumps, it often is not. [QUOTE]

hence the tune up with new pump and injectors and properly set timing comments.




[QUOTE=jdemaris;15595601]And of course you can just guess if the pump is suspect, you can remove it and spend maybe close to $900. Then hope it is better and still not know for sure. And that money gets you a so-called "rebuilt" pump with very few moving parts renewed in any way. Just resealed, calibration checked, and a few small parts replaced as needed. Often the low pressure pump vanes and some advance-piston parts. Often the main high-pressure parts of the pump have many, many miles on them and are re-used, as is. It gets expensive.[QUOTE]

that is why you buy quality parts from a vendor with a steller reputation. and those pumps are under $600, not "close to $900"


[QUOTE=jdemaris;15595601] The bright side is - these main parts can last 1,000,000 miles if the fuel has good lube. Not so sure now adays with the ultra-low sulfur stuff. I still add two-stroke oil to my tank as added insurance.[QUOTE]

ULSD has better lubrication additives than regular high sulfur diesel ever had.
with the old high sulfur diesel i was lucky to get 120k miles out of injector pumps. with the ULSD i get at least 150 k miles.

 

thank you tjc for tackling that....I sure as hell didn't feel like it.


the idea of the factory optimizing exhaust is ridiculous, especially in the time period of the discussion.


designers look at a few major things when designing a system, and it is not limited to exhaust. to think otherwise is silly...


1) cost
2) production (can it be made and installed with ease)
3) laws/restrictions: emissions, noise, etc
5)effectiveness


none of the lower things on the list will jeopardize the things that are higher. so yea, stuff that leaves the factory can be pretty awful, and there are hundreds of examples of poor performing pieces from the factory whether it be exhaust, heads, cam, intake, compression, and hell...pretty much anything else.


one thing across the board that are restrictive, especially on a large engine, are gigantic mufflers.

 

[QUOTE=tjc transport;15597370]ford used a navastar diesel, not international harvester. different company.
GM used a GM diesel, and later an izuzu diesel. (duramax) not a detriot diesel different companies.

dodge only used the mitsushi for one year, it was a disastrous flop, and did not put a diesel in a pickup for over 7 years before going with the cummins 5.9


any vehicle made in the past 40 years has had a very restrictive exhaust on it thanks to the EPA. open the exhaust up so it is free flowing and you wake the engine up.

[QUOTE=jdemaris;15595601]Anybody who can do a little math can use the volumetric efficiency figures of a naturally aspirated diesel and then figure the flow needs of the exhaust. Or if no math, just use a computer-based calculator. I've checked quite a few. Found very few factory exhaust systems on HD (somewhat EPA exempt) trucks that caused the loss of any substantial horsepower with stock engine. Now - when someone had to put their first replacement system on and bought their mufflers at NAPA - all bets are off. I've found many aftermarket replacement mufflers and pipes to rob some power and raise exhaust port temps.[QUOTE]

we said high flow low-back pressure exhaust, not aftermarket replacement.






[QUOTE=jdemaris;15595601]Also - about the static timing specs mentioned here. What good are they if you don't know what the heck the timing advance is doing when the truck is actually being driven? All that initial static timing does is ensure the timing is correct when the engine is cranking or at low idle speed. Has pretty much nothing to do with the injection timing when the truck is being used. That is, unless you already know 100% for sure the advance curve is working properly. On older pumps, it often is not. [QUOTE]

hence the tune up with new pump and injectors and properly set timing comments.




[QUOTE=jdemaris;15595601]And of course you can just guess if the pump is suspect, you can remove it and spend maybe close to $900. Then hope it is better and still not know for sure. And that money gets you a so-called "rebuilt" pump with very few moving parts renewed in any way. Just resealed, calibration checked, and a few small parts replaced as needed. Often the low pressure pump vanes and some advance-piston parts. Often the main high-pressure parts of the pump have many, many miles on them and are re-used, as is. It gets expensive.[QUOTE]

that is why you buy quality parts from a vendor with a steller reputation. and those pumps are under $600, not "close to $900"


[QUOTE=jdemaris;15595601] The bright side is - these main parts can last 1,000,000 miles if the fuel has good lube. Not so sure now adays with the ultra-low sulfur stuff. I still add two-stroke oil to my tank as added insurance.

 

[QUOTE=jdemaris;15597848]International Harvester got renamed "Navigating the Stars." That name was quickly dumped and then morphed into "Navistar." Same basic company as far as truck engines go, same materials, same engines regardless if the IH name was used or those names that came later. Not sure what your point is? Yes, IH sold off their IH name mid-80s and used a new one. Engines were made in the same place by the same workforce with the same tooling.

The only diesel that any General Motors auto company designed totally "in house" for cars and light trucks was the 5.7 series done by the Oldsmobile division. GMC did the Toroflow for heavier trucks. The 6.2 diesel that came out in 1982 was totally designed by Detroit Diesel for GM. It was designed as a direct power replacement for GM's 305 automotive gas engine with the same footprint and better fuel efficiency. You've got your facts wrong. Detroit Diesel was a division of General Motors at that time and it created the 6.2.
Isuzu was partly owned by GM for many years and built many engines for it's part-owner, GM. I still have my 1981 diesel Chevette with a 1.8 Isuzu engine.
Duramax was a joint venture where GM and Isuzu engineers worked together.


[QUOTE=jdemaris;15597848]Hey, believe whatever you want. I don't believe it and I've been working on cars, diesels, and heavy equipment for 50 years. Why would the EPA care about exhausts that flow too much? Makes no sense to me. Emissions is the concern. Not horsepower, torque, or how "unrestrictive" and exhaust system is. Like I said, do the math. A diesel engine that rarely runs past 2600 RPM does not need a tremendous amount of flow. Again - anytime any system is in question - it just takes a few minutes to calculate the CFM of exhaust needed. Also takes just a few minutes to calculate the CFM flow capabilities of what you have. I've checked a few OEM systems and they were fine on stock engines. Can you name one specific system that robbed engine power on a stock engine due to restriction and if so - by how many CFM?


[QUOTE=jdemaris;15597848]Hmmm. Name me even one pump seller that offers Stanadyne rotary pumps for the 7.3 diesel with new main moving parts inside for "under $600?" I bet you cannot name a single one. Dealers that are selling patched up pumps with highly used head & rotors, yes. Prove me wrong. In fact. if you can direct me to a seller with a pump for my 1994 IDI turbo diesel with a new head & rotor inside (main moving part) and also new pump liner, vanes, and advance parts - for under $600 - I'm going to buy one for a spare. I worked in several pump shops and I find it hard to imagine anyone selling that cheap unless some place in China is selling head & rotor assemblies for $100.
Last time I checked (it's been awhile) - if trading in your old pump for a "core" - it was required to have a good head & rotor or no core-credit given. Now, maybe since these trucks are getting old - some sellers are willing to sell cheaper to get off their shelves.